9/9/2013
Information for well owners
The National Ground Water Association encourages water well owners to test the quality of
their water regularly.
As oil and gas development increases around the country, NGWA reminds water well owners
about the importance of testing their water wells prior to oil and gas well installation. This provides a
baseline for comparison after oil and gas production.
Relationship of hydraulic fracturing for oil or gas development and
groundwater used for drinking supply
Hydraulic fracturing has captured headlines in areas where gas development is occurring.
Hydraulic fracturing is a petroleum-industry process in which fluids, commonly made up of water
and a small percentage of chemical additives, are combined with sand and are pumped at very
high pressure into a geologic formation holding gas. The resulting fractures allow the release of
natural gas, which can be collected.
A 2004 U.S. Environmental Protection Agency study of hydraulic fracturing of coalbed methane
reservoirs found little or no threat to underground sources of drinking water. Currently, the U.S. EPA
is studying whether hydraulic fracturing adversely affects groundwater quality as the practice expands
rapidly into other types of geologic formations, particularly shales. A draft report is expected to be
released for public comment and peer review in 2014. The primary questions the U.S. EPA hopes to
answer in the study are:
• What hydraulic fracturing scenarios might cause impacts on drinking water resources?
• What approaches are effective for protecting drinking water?
Suggested options for water well owners
NGWA suggests all water well owners regularly test their water quality because:
• Many areas of the United States have geologic conditions that release natural constituents into
groundwater.
• Water quality in private wells is not regulated by the federal government or by many state and
local governments.
• Below-ground activities such as oil and gas drilling can potentially affect their drinking water
quality.
It is difficult to give a universal recommendation for water testing that proves damage to a well
has occurred. This is because the rate at which groundwater flows and the risk of water well contamination depend on site-specific geology, among other factors. NGWA encourages water well
owners to review additional sources of information that may be relevant to your specific circumstances, or the state or county where you reside. One such information source will be listed later in
this brief.
®
Phone/ Toll-free 800 551.7379/ 614 898.7791 Fax/ 614 898.7786
Web/ www.ngwa.org and www.wellowner.org
Address/ 601 Dempsey Road/ Westerville, Ohio 43081-8978 U.S.A
NGWA Information Brief
Water Wells in Proximity to
Natural Gas or Oil Development
For some water well owners, the cost of water testing may be an issue. In the rare cases where
regulatory or legal action is necessary, a comprehensive analysis is often better. However, water
testing—especially for organic chemicals or chemicals in minute amounts—can be expensive.
NGWA has compiled a list of constituents to test in areas of oil or gas development. It includes
the major ions in groundwater, which consist of calcium, magnesium, sodium, potassium, alkalinity
(bicarbonate and carbonate), sulfate, and chloride. These usually make up more than 90% of all
dissolved constituents in groundwater, and are used to define a water “type”—similar to labeling
blood types. Analyzing this suite of ions both pre- and post-drilling allows for quantitative changes
in water quality to be determined.
Bromide is an ion common to brackish water and brines. A measure of the ratio of bromide to
chloride has been used to “fingerprint” saltwater—for example, to help distinguish whether salt
contamination in a water well is from road salt or contamination from oil brines.
Barium is a potentially harmful element that sometimes can be an indicator of radioactive
elements in oil brines or production fluids.
Uranium is a radioactive element that can occur naturally in groundwater or be released from a
geologic formation by contamination from brine.
The pH of water is a measure of the water’s acidity or alkalinity, and can cause the release of
other undesirable metals, such as iron, into groundwater.
The total dissolved solids (TDS) is a measure of the sum of all dissolved constituents in water.
It can be used to compare samples for any net increase in salt or other dissolved constituents. It
also can be used to see if all of the changes in subsequent water sampling have been accounted
for, since the TDS should about equal the sum of all other dissolved constituents in the sample.
If it doesn’t, then there may be other constituents in the water that have been overlooked.
The specific conductance is a measure of the electrical current that can be transmitted by the
water, and is directly proportional to the amount of dissolved solids. It can be used in subsequent
sampling as a cost-effective screening tool to determine if more comprehensive sampling may be
needed.
Iron, manganese, selenium, chromium, arsenic, and boron are other naturally occurring
minor and trace elements that may cause cosmetic or ill health effects to consumers. An increase
in the concentration of these constituents may indicate changes in the aquifer due to the drilling
process or stimulation fluids.
Organic chemicals such as toluene, benzene, oil, and grease may be by-products of oil and gas
production, or well stimulation activities.
Methane is a naturally occurring gas that can dissolve into groundwater. It is common to areas
with oil and gas development because the rocks underlying these areas by nature contain petroleum,
natural gas, and coal. Methane can seep to the surface and into fresh groundwater under natural
conditions. Processes near the earth’s surface (e.g., decomposition of organic matter in swamps
and wetlands) can also produce methane, so the mere presence of methane in well water does not
immediately indicate contamination related to oil and gas production.
However, an unusual change in the amount of methane in water may indicate changing
conditions underground. In this case, enhanced analysis of the gas can help determine its origin.
Turbidity is a measure of the cloudiness of a water sample from suspended particles, and may
indicate disruption of the flow system that provides water to a well.
NGWA has developed Best Suggested Practices (BSPs) for groundwater professionals on topics
that include reducing problematic concentrations of arsenic, boron, iron and manganese, methane,
and uranium in well water. NGWA also has developed a BSP for reducing problematic concentrations of methane in residential water well systems.
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It is important to collect a sample before oil and gas drilling in your area to establish the baseline
conditions of your groundwater supply. It is also important to test after completion of drilling
activities. Some states require energy companies to collect samples and may have time limits for
sample collection. So, each water well owner should contact their state or local regulatory authority
to find out about any requirements.
States also may have agreements with energy companies detailing constituents that the company
will cover for pre- and post-drilling well water quality testing. In the absence of such programs,
the list in this brief provides constituents to test in order to establish a water quality baseline.
Following are steps well owners can take before and after oil and gas production takes place.
Step 1. Prior to oil and gas operations, have a professional, such as a qualified water well system
professional, test your groundwater quality for appropriate constituents to establish a water quality
baseline for post-fracturing or drilling analysis.
When seeking a qualified drinking water testing lab, check with your state or local health
department, or go to NGWA’s Web site www.wellowner.org and click on “Water Quality” on the
menu and then “Water Testing” beneath. If local labs do not test for substances you wish to check,
there are national water testing labs that may be able to help, such as the National Testing Labs
(www.ntllabs.com) and Underwriters Laboratories (www.ul.com).
Step 2. In the absence of a list developed specifically for your area by a credible source, the
following list from NGWA includes basic constituents that should be considered for water quality
analysis prior to oil and gas operations.
Major Ions:
alkalinity, calcium, chloride, magnesium, potassium, sodium, sulfate
Minor and Trace Elements:
arsenic, barium, boron, bromide, chromium, iron, manganese, selenium, uranium
Water Quality Parameters:
pH, specific conductance, total dissolved solids (TDS), turbidity
Organic Chemicals:
benzene, toluene, ethyl benzene, xylene (BTEX); diesel range organics (DRO); dissolved methane;
gasoline range organics (GRO); total petroleum hydrocarbons or oil and grease (HEM)
Examples of other localized water quality testing recommendations can be found at http://
wri.eas.cornell.edu/gas_wells_5_1489175471.pdf.
When testing for the presence of dissolved methane, multiple analyses conducted over time may
be needed to properly establish a baseline.
Step 3. Once hydraulic fracturing has taken place, water well owners should consider retesting
their water quality against the baseline results and against any additional fracturing fluid chemicals
that have been voluntarily disclosed. The Ground Water Protection Council (GWPC) Frac Focus
Web site (http://fracfocus.org) lists chemicals used in fracturing fluids voluntarily disclosed by
some companies.
To learn more about laws regarding disclosure of chemicals, visit GWPC’s “Chemicals and
Public Disclosure” and “Find a Well by State” sections of its Frac Focus Web page.
Post-drilling water quality testing should be done within six months of completion of drilling and fracing. Continued sampling should be done at least annually as long as practicable. Subsequent screening
using the pH and specific conductance, or total dissolved solids measurements, can be less expensive
ways to see if changes have occurred. An increase in the concentration or occurrence of these constituents could indicate that further, more sophisticated water quality testing should be done.
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You can learn more about the toxicity of chemicals by searching for the chemical using the
name or CAS number on the U.S. EPA National Center for Computational Toxicology Web site.
The U.S. EPA also maintains a Drinking Water Hotline that is available Monday through Friday
from 8:30 a.m. to 4:30 p.m. ET at 800 426.4791. Only a trained water quality professional can tell
you if your water is safe to drink.
What to do if water quality changes
If there is a change in water quality, the well owner should discuss it with local or state health or
environmental protection authorities.
Most constituents can be treated by in-home systems. When considering a water treatment
device, make sure its specifications match the substances and concentrations you wish to treat.
You may want to check with the Water Quality Association (www.wqa.org) and NSF International
(www.nsf.org) to determine whether the technology being considered has been performance tested.
References
Hydraulic Fracturing EPA Public Information Meeting, Binghamton, New York. September 15, 2010.
Summary of Public Comments. http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/
upload/hfsummarybinghampton3.pdf
National Ground Water Association. 2013. Reducing Problematic Concentrations of Boron in Residential
Well Systems. Westerville, Ohio. NGWA Press.
National Ground Water Association. 2013. Reducing Problematic Concentrations of Iron and Manganese in
Residential Water Well Systems. Westerville, Ohio. NGWA Press.
National Ground Water Association. 2013. Reduce and Mitigate Problematic Concentrations of Methane in
Residential Water Well Systems. Westerville, Ohio. NGWA Press.
National Ground Water Association. 2010. Reducing Problematic Concentrations of Arsenic in Residential
Well Systems. Westerville, Ohio. NGWA Press.
National Ground Water Association. 2010. Reducing Problematic Concentrations of Uranium in Residential
Well Systems. Westerville, Ohio. NGWA Press.
U.S. EPA, 2010. Evaluation of Impacts to Underground Sources of Drinking Water by Hydraulic Fracturing
of Coalbed Methane Reservoirs Study (2004). http://water.epa.gov/type/groundwater/uic/class2/hydraulic
fracturing/wells_coalbedmethanestudy.cfm
U.S. EPA, 2010. Hydraulic Fracturing Background Information. http://water.epa.gov/type/groundwater/uic/
class2/hydraulicfracturing/wells_hydrowhat.cfm
U.S. EPA, 2010. Opportunity for Stakeholder Input on EPA’s Hydraulic Fracturing Research Study: Study
Design. http://www.epa.gov/indian/pdf/discussion-document-study-design.pdf
Disclaimer: This NGWA Information Brief is provided as a service and is not intended to offer
legal advice whatsoever. The National Ground Water Association and its agents disclaim any and
all liability for damages attributable to this information brief.
© 2013 by the National Ground Water Association. All rights reserved.
Revised 9/9/2013
The National Ground Water Association is a not-for-profit professional society and trade
association for the groundwater industry. Our 12,000 members from all 50 states include some
of the country’s leading public and private sector groundwater scientists, engineers, water well
contractors, manufacturers, and suppliers of groundwater-related products and services. The
Association’s vision is to be the leading groundwater association that advocates the responsible
development, management, and use of water.
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